Device manufacturing method

Abstract

A method of manufacturing devices with device layers on both sides of a substrate according to an embodiment of the invention includes ensuring that the movements of the substrate during the exposure of the backside are a mirror image of the movements during the exposure of the frontside. In an application of such a method, positioning errors that are characteristic of direction of movement are thus reversed in the backside exposure as compared to the frontside exposure, such that the net overlay error between front and backside is zero or near zero. Embodiments of the invention may be used to reduce overlay errors arising out of certain types of positioning error at no cost, either in machine modifications or throughput.

1. A device manufacturing method comprising:
 projecting at least one pattern onto a first series of target portions on a first side of a substrate; 
 rotating the substrate about an axis; and 
 projecting at least one pattern onto a second series of target portions on a second side of the substrate, said second series of target portions corresponding to said first series of target portions; 
 wherein relative movements of said substrate during said projecting at least one pattern onto a second series of target portions are a mirror image about said axis of relative movements of said substrate during said projecting at least one pattern onto a first series of target portions. 
 
     
     
       2. The device manufacturing method according to  claim 1 , wherein a plurality of patterns are projected onto said first series of target portions to build up a device from a plurality of layers, and
 wherein during projection of all of said plurality of patterns the same movement pattern is used. 
 
     
     
       3. The device manufacturing method according to  claim 2 , wherein a plurality of patterns are projected onto said second series of target portions to build up a device from a plurality of layers, and
 wherein during projection of all of said plurality of patterns the same movement pattern, being a mirror image of the movement pattern used during projection onto the first series of target portions, is used. 
 
     
     
       4. The device manufacturing method according to  claim 1 , wherein the whole of each target portion is exposed at once whilst the substrate is still. 
     
     
       5. The device manufacturing method according to  claim 1 , wherein each target portion is exposed during a scanning movement of the substrate relative to a projection system. 
     
     
       6. The device manufacturing method according to  claim 5 , wherein the scanning movement of the substrate during each exposure of said second series of target portions is a mirror image of the scanning movement during exposure of the corresponding target portion of said first series. 
     
     
       7. The device manufacturing method according to  claim 5 , wherein said axis is parallel to the direction of relative motion of said substrate during said scanning movement. 
     
     
       8. The device manufacturing method according to  claim 1 , wherein the axis is a diameter of the substrate. 
     
     
       9. The device manufacturing method according to  claim 1 , wherein said rotating comprises rotating the substrate about an axis by 180 degrees between said projecting at least one pattern onto a first series of target portions on a first side of a substrate and said projecting at least one pattern onto a second series of target portions on a second side of the substrate. 
     
     
       10. A device manufacturing method comprising:
 transferring a pattern onto each of n target portions on a first side of a substrate in sequence from 1 to n; and 
 transferring a pattern onto each of n target portions on a second side of a substrate in sequence from 1 to n, 
 wherein for each i from 1 to n, the i-th target portion on the first side is substantially directly opposite the i-th target portion on the second side. 
 
     
     
       11. The device manufacturing method according to  claim 10 , wherein at least one of said transferring a pattern onto each of n target portions on a first side and said transferring a pattern onto each of n target portions on a second side comprises projecting a pattern onto each of the n target portions. 
     
     
       12. The device manufacturing method according to  claim 10 , said method comprising rotating the substrate about a diameter of the substrate. 
     
     
       13. The device manufacturing method according to  claim 12 , said method comprising rotating the substrate by 180 degrees about a diameter of the substrate. 
     
     
       14. The device manufacturing method according to  claim 12 , wherein said transferring a pattern onto each of n target portions on a first side comprises, for at least one of the n target portions, moving the substrate parallel to the diameter during said transferring. 
     
     
       15. The device manufacturing method according to  claim 10 , wherein said transferring a pattern onto each of n target portions on a first side comprises, for at least one of the n target portions, exposing a pattern onto the target portion while the substrate is still. 
     
     
       16. The device manufacturing method according to  claim 10 , wherein said transferring a pattern onto each of n target portions on a first side comprises, for at least one of the n target portions, exposing a pattern onto the target portion while the substrate is moving. 
     
     
       17. The device manufacturing method according to  claim 10 , wherein said transferring a pattern onto each of n target portions on a first side of a substrate in sequence from 1 to n includes moving at least one of the substrate and the pattern relative to the other, in a plane substantially parallel to the first side, in a first path including movement between each consecutive pair of transfers in the sequence, and
 wherein said transferring a pattern onto each of n target portions on a second side of the substrate in sequence from 1 to n includes moving at least one of the substrate and the pattern relative to the other, in a plane substantially parallel to the first side, in a second path including movement between each consecutive pair of transfers in the sequence, and 
 wherein the second path in its plane is substantially identical to the first path in its plane. 
 
     
     
       18. The device manufacturing method according to  claim 17 , said method further comprising transferring another pattern onto each of the n target portions on the first side of the substrate in sequence from 1 to n,
 wherein said transferring another pattern onto each of the n target portions on a first side of a substrate includes moving at least one of the substrate and the pattern relative to the other, in a plane substantially parallel to the first side, in the first path. 
 
     
     
       19. The device manufacturing method according to  claim 18 , said method further comprising transferring another pattern onto each of the n target portions on the second side of the substrate in sequence from 1 to n,
 wherein said transferring another pattern onto each of the n target portions on the second side of the substrate includes moving at least one of the substrate and the pattern relative to the other, in a plane substantially parallel to the first side, in the second path. 
 
     
     
       20. A storage medium storing a set of machine-executable instructions, said set describing a device manufacturing method comprising:
 transferring a pattern onto each of n target portions on a first side of a substrate in sequence from 1 to n; and 
 transferring a pattern onto each of n target portions on a second side of a substrate in sequence from 1 to n, 
 wherein for each i from 1 to n, the i-th target portion on the first side is substantially directly opposite the i-th target portion on the second side.